With the advent of increasingly sophisticated telecommunication services, various proposals have been made to allow a single call, incoming to a telecommunication switch, to branch into multiple, independent outgoing calls (or legs) to different called parties, during the same period of time. These incoming and multiple outgoing calls may be wireline, such as PSTN (public switched telephone network), ISDN (integrated services digital network), or T1/E1 wireline calls, or may be wireless, such as cellular calls or other mobile service communications.
Once such proposal is included in the ANSI-41 specification promulgated by the American National Standards Institute for wireless telecommunication, such as cellular communication, and is referred to as "flexible alerting". The ANSI-41 flexible alerting specification, however, does not include any specific directions or guidelines for implementation and control of such independent, concurrent outgoing multiple leg calls.
Other prior art systems also do not provide for multiple outgoing calls, to different parties, during the same time period. Rather, such known systems provide for individual, sequential calls rather than multiple, concurrent outgoing calls. For example, the incoming call may first alert a home telephone having a first directory number; if the first call is unanswered, that call leg is dropped and a second telephone having a different, second directory number is alerted, such as a cellular phone. If the second call is unanswered, that second call leg is dropped, and a third line having a third directory number is alerted, such as a pager.
In such flexible alerting or other systems having multiple, independent outgoing call legs from a single incoming call leg, whichever outgoing call leg is first to answer will receive the call and be connected to the calling party, with the other call legs being released (i.e., dropped or torn down, with their corresponding alerting ceased). In addition, the end units or terminating customer premise equipment (such as wireline telephones and wireless or mobile telephones) of the subscriber receiving the outgoing call legs preferably also receive direct calls in addition to such flexible alerting calls. A particular difficulty with such multiple outgoing call legs arises because such a subscriber or other customer may have different requirements for direct calls rather than flexible alerting calls. For example, a subscriber may want direct calls forwarded to a voice mail system when the line is busy, but may want an outgoing call leg of a flexible alerting session to be released on busy, so that the call may be answered by another member of the flexible alerting group. As a consequence, such flexible alerting calls may require different treatment than that afforded by a distant switch implementing various end unit services, such as voice mail or call forwarding services.
As a consequence, a need remains for an apparatus, method and system to implement and control multiple, independent outgoing communication sessions (or call legs) originating from a single incoming call leg. Such an apparatus, method and system should also provide for control of secondary treatment by a distant or terminating switch for the multiple, independent outgoing communication legs or links. Such an apparatus, method and system also should be user friendly and user transparent.